Motor Branch Circuit Protection
Motor circuit protection describes the short-circuit protection of conductors supplying power to the motor, the motor controller, and motor control circuits/conductors.
430.52 provides the maximum sizes or settings for overcurrent devices protecting the motor branch circuit. A branch circuit is defined in Article 100 as “The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s).”
| Type of Motor | Non-Time-Delay Fuse | Dual Element (Time-Delay)Fuse | Instantaneous Trip Breaker | Inverse Time Breaker |
| Single-phase motors | 300 | 175 | 34 | 7 |
| AC polyphase motors other than wound-rotor | 36 | 9 | ||
| Squirrel Cage: Other than Design E | 300 | 175 | 40 | 13 |
| Squirrel Cage: Design E | 300 | 175 | 42 | 15 |
| Synchronoust | 300 | 175 | 44 | 17 |
| Wound Roto | 150 | 150 | ||
| Direct-current (constant voltage | 150 | 150 |
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